Abstract The application of inhibitors against metals and alloys corrosion in various aggressive environments is an excellent solution. The present study explored Cu corrosion inhibition in a 0.5 M H2SO4 solution by MP EO, from Western Morocco, using EIS and PDP analyses. GC coupled with MS revealed that MP EO is mainly composed of pulegone (23.38%), isomenthone (20.54%) and l-menthone (9.56%). MP inhibitory behavior was of mixed type. MO EO prevented Cu corrosion in H2SO4, with an IE(%) that increased with its Ct, at a maximum of 91.0%, with 1 g/L. The Cu surface was studied by SEM coupled with EDS.

Abstract In the present work the influence of the two organic inhibitors, namely : phenyl (2- (3,4,5 trimethoxyphenyl) -1H-benzo [d] imidazol-1-yl) methanone (P3) and ( 2- (4 -methoxyphenyl) -1H-benzo [d] imidazol-1-yl) (phenyl) methanone (P4) on the ordinary steel corrosion in 5.0 M HCl solution was investigated by using electrochemical measurements, scanning electron spectroscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDX), UV-visible spectroscopy and theoretical study. The obtained results showed that these compounds act as mixed inhibitors. It is obtained that the inhibition efficiency increases with their concentrations and reaches 97.0% and 91.3% at 10−3 M of P3 and P4, respectively. These findings were confirmed by the electrochemical impedance spectroscopy measurements, where the transfer resistance values increase with the concentrations. In addition, the effect of temperature range from 298 K to 328 K was investigated and indicated that P3 and P4 keep their performance at height temperature. Moreover, density functional theory explained the relationship between the molecular structure of imidazole derivatives and inhibition performance obtained experimentally. Additionally, the morphological surface and EDX analyses indicated that these compounds act by the formation of a protective layer on the ordinary steel surface. In order to confirm the possibility of the formation of P3-Fe and P4-Fe complexes, the UV–Visible absorption spectra was used. The obtained results indicated the formation of a complex between Fe2+ and molecules inhibitors.

The corrosion inhibition of mild steel in a 1.0 M hydrochloric acid solution by 2-(4,5diphenyl- 4,5-dihydro-1h-imidazol-2-yl)-5-methoxyphenol (P1) has been studied in relation to the concentration of the inhibitor, as well as to the temperature, using chemical (weight loss) and electrochemical techniques. All the employed methods were in reasonable agreement. The protection efficiency increased with an increased inhibitor's concentration. The obtained thermodynamic adsorption parameters (ΔG*ads, ΔH*ads, ΔS*ads) indicated that this polymer retarded both cathodic and anodic processes through physical adsorption, and blocked the active corrosion sites. It was also found that this compound obeyed the Langmuir's adsorption isotherm.